The present invention is directed to a method and means for the forming and progressive joining (as by sewing, adhering, fusing, etc.) of hems on fabric articles, particularly articles of tubular construction. The invention has particular applicability to the forming and joining of hems on pillowcases and the like, but many of its principles may be utilized to advantage in the manufacture of other articles, both tubular and in some cases non-tubular. While the specific illustrations of this application relate to the processing of pillowcases, it will be understood throughout that at least certain aspects of the invention are not limited thereto.
In the production of a typical pillowcase, for example, it is conventional to form a so-called large hem, typically of one to four inches in length at the open end of the case. The raw edge of the fabric forming this large hem is then tucked under to form a blind or "small" hem having a width on the order of 1/4 inch or so. The case is stitched in the margin of the underfolded small hem, so that both the large and small hems are secured in place by a single line of stitching. In addition, it is customary for an identifying label to be inserted under the hem and secured by the hem stitching, usually in the region of the side seam of the pillowcase.
In accordance with the present invention, a facility is provided for the highly automated forming and securing of the large hem and small hem folds of a pillowcase, and for performing similar operations on other articles. The apparatus of the invention includes a pair of freely rotating drums, constituting inner forms, which are arranged to receive the open end of the pillowcase and accommodate its free movement in a circumferential direction. Adjacent and outside the drums are arcuate plates, closely embracing the rotatable drums about a portion of their peripheries but spaced slightly therefrom. The arcuate plates and the drums, constituting outer and inner forms repsectively, are arranged to be received internally of a tubular pillowcase and arranged to be urged apart under controlled pressure to apply circumferential tension to the hem forming region of the case. When the pillowcase is thus positioned, hem forming shoes of arcuate configuration are inserted axially in the arcuate spaces between the outer and inner forms to effect an outward fold of an end margin of the pillowcase, thereby forming the large hem. When the shoes are withdrawn, the pillowcase remains supported under tension on the spaced, freely rotatable drums, in a position to be advanced circumferentially to effect sewing and other operations. As one of the more specific aspects of the invention, advantageous arrangements are provided for urging the article holding drums in a separating direction, to apply circumferential tension to the article, without danger of damaging the side seam thereof. In general, the structure described in this paragraph is claimed in our parent U.S. Pat. No. 3,865,058.
In accordance with the invention, and as a significant feature of the present application, novel arrangements are provided for injecting air into the interior of the pillowcase, while it is movably supported on the rotatable drums, to partially inflate the case and facilitate its manipulation during the performance of further operations.
To effect the formation of the infolded small seam, the apparatus of the invention includes a novel small seam folder which is uniquely adapted to effect the initiation of the small seam folding action in a tubular article, such as a pillowcase. The small seam folder device is arranged for a three-stage startup action. In the first two stages, separate, sequentially arranged sections of the small seam folder are advanced, axially of the tubular article, into engagement with the raw edge area of the large hem. The first stage of the folder serves to effect approximately 90.degree. of the required fold, while the second stage engages the prefolded edge and completes the 180.degree. hem fold. In addition, since the small hem folder is aligned with and precedes the sewing station, the invention provides for a third stage of operation, in which the small hem folder is reciprocated in a circumferential direction to and beyond the sewing foot, and then returned. The arrangement is such that, prior to the commencement of a sewing operation, the inturned small hem fold is made to underlie the sewing foot, and the stitching will at the outset engage a properly folded margin of small hem.
To advantage, a label inserting device is synchronized with the initiating operations of the small hem folder, enabling a desired identifying label to be inserted under the sewing foot prior to the commencement of sewing operations. Desirably, then, the label is provided with a row of stitching at the outset, and also at the termination of the sewing operation, such that a limited, desired degree of stitch overlap will occur within the confines of the label.
As another feature of the invention, there is provided an advantageous sewn-seam detector facility operative, as the hem seaming operation nears completion, to sense the approach of the starting point of the stitching and cause the sewing operation to be terminated with the desired, limited degree of overlap. Usually, although not necessarily, it is desirable that the area of stitch overlap coincide with the position of the label, making it less obtrusive. The novel sewn-seam detector includes an element received under the folded hem, on the "upstream" side of the sewing foot, lying in the path of the stitching. As the starting point of the seam reaches the detector element, continued advancement of a pillowcase or other article causes the detector to be physically displaced to control termination of the sewing operation. The special arrangement of the invention enables an effectively continuous circumferential seam to be formed with a controlled minimum overlap, sufficient to derive a desired degree of interlocking of the seam ends.
The invention also includes an advantageous form of device for sensing failure of the sewing machine to properly effect the seaming operation, whether by reason of thread break or otherwise. The new arrangement takes advantage of the fact that the fabric is held under tension, extended unsupported across a predetermined span, between the spaced drums. The main portion of the fabric is forcibly deflected out of the plane which it seeks under tension, and a movable sensing element engages the sewn hem in an adjacent area. As long as the hem is attached to the body of the fabric by proper stitching, the hem will follow the deflected contours of the main portion of the fabric. However, if the sewing machine is not functioning properly, for any reason, and the hem is not being secured to the body of the fabric, the hem will return to the tension plane, while the body of the fabric will continue to be deflected. The spaced relationship between the adjacent portions of fabric is easily sensed, and an appropriate control function is derived therefrom.
At the end of the hem sewing operation, an extender element is projected into the blind or closed end of the pillowcase, automatically effecting its axial withdrawal from the supporting drums. A stacker device, located in front of the machine, is arranged to engage the leading edge of the pillowcase and withdraw it from the extender bar for folding and collection. The method and apparatus of the invention are highly versatile, and accommodate the forming of hems of various widths in connection with pillowcases and other tubular articles in particular. As will become apparent, however, certain principles of the invention are applicable to the processing of non-tubular articles.
For a better understanding of the above and other features of the invention, reference should be made to the following detailed description of a preferred embodiment of the invention, and to the accompanying drawings.